The invention relates to apparatus for a guiding rope as it is being wound on to and off of a drum. The invention also relates to mining equipment, such as draglines, and to fairlead mechanisms for such equipment.
A dragline generally comprises a main housing that supports a boom 300 to 400 feet long. A sheave is rotatably mounted adjacent the top of the boom. A main lift rope such as a steel wire rope or cable has one end connected to a hoist drum on the main housing, and the lift rope is reeved over and suspended from the sheave at the top of the boom. A dragline bucket is connected to the other end of the main lift rope and is raised and lowered by actuation of the hoist drum.
A drag rope has one end connected to the dragline bucket and another end connected to a drag rope drum on the main housing. The drag rope is typically a wire wound rope or cable which may be up to 4.5 inches in diameter and have a length of 600 to 700 feet. The drag rope drum is selectively energized by the dragline operator to pull the dragline bucket toward the main housing to load the bucket. The drag rope drum is also operative to release the drag rope for travel away from the main housing in order to permit the loaded bucket to be dumped or to permit an empty bucket to be moved to a desired working position.
During operation the dragline bucket may be raised in order to spoil overburden high on a spoil pile, or to reclaim a spoil pile, or the dragline bucket may be lowered down into a mine pit for loading. The lateral swinging movements and the vertical up and down movements of the dragline bucket cause the drag rope to have both a vertical and a horizontal angular sweep of travel relative to the drag rope drum. During the vertical and horizontal sweeping movements the drag rope also moves toward and away from the main housing, and travel of the drag rope is guided to minimize undesirable contact with the main housing, the ground, and other dragline components. This guiding of the drag rope is accomplished by what is commonly known as a fairlead mechanism.
A typical fairlead mechanism is mounted on the main housing platform that supports the drag rope drum. The fairlead mechanism includes a pair of side-by-side horizontal sheaves mounted on the platform for rotation about respective vertical axes, and a pair of upper and lower vertical sheaves mounted on a subframe that is pivotally mounted on the platform for oscillatory movement about a generally vertical axis. The upper and lower sheaves are mounted on the subframe for rotation about respective horizontal axes. The planes in which the horizontal and vertical sheaves lie are arranged at right angles relative to each other. The drag rope, upon leaving the drag rope drum, first passes between the facing grooves of the horizontal sheaves and then between the facing grooves of the vertical sheaves. The horizontal sheaves can weigh up to 11,200 lbs. each and the vertical sheaves up to 13,300 lbs. each. Usually a dragline will utilize two or more drag ropes and a corresponding number of fairlead mechanisms.
The invention provides a fairlead mechanism having many advantages over prior art mechanisms. The invention: decreases the number of component parts of the mechanism; increases interchangeability of component parts; decreases the cost of the mechanism; decreases the number of parts contacting the drag rope, thereby reducing rope wear and increasing rope life; positions the drag rope higher on the machine, thereby reducing rope wear due to contact with the ground; uses smaller and lighter components, thereby reducing the forces necessary to operate the machine; decreases the inertia of the sheaves, thereby reducing over-running and sliding damage to the rope; and decreases the operating cost of the machine.
More particularly, the invention provides an apparatus comprising a platform, a winding drum mounted on the platform for rotation relative thereto, a rope which is wound around the drum and which extends away from the drum, and a device for guiding the rope as the rope extends away from the drum, the device including a first sheave mounted on the platform for pivotal movement about a first axis generally perpendicular to the platform, the first sheave also being supported for rotation about a second axis generally parallel to the platform, and a second sheave mounted on the platform for pivotal movement about the first axis independently of the first sheave, the second sheave also being supported for rotation about a third axis generally parallel to the platform, and the rope extending at least partially around the first and second sheaves.
The invention also provides a dragline comprising a main housing including a generally horizontal platform, a boom extending forwardly from the main housing, a bucket suspended from the boom, a winding drum mounted on the platform for rotation about a generally horizontal axis, a rope which is wound around the drum and which extends away from the drum to the bucket for moving the bucket generally horizontally relative to the main housing, and a fairlead mechanism including a first sheave mounted on the platform for pivotal movement about a generally vertical first axis, the first sheave also being supported for rotation about a generally horizontal second axis, and a second sheave mounted on the platform for pivotal movement about the first axis independently of the first sheave, the second sheave also being supported for rotation about a generally horizontal third axis, and the rope extending at least partially around the first and second sheaves.
The invention also provides a dragline comprising a main housing including a generally horizontal platform, a boom extending forwardly from the main housing, a bucket suspended from the boom, a winding drum mounted on the platform for rotation about a generally horizontal axis, a fairlead mechanism including an upper sheave mounted on the platform for rotation about a generally horizontal axis, and a lower sheave mounted on the platform for rotation about a generally horizontal axis, and a rope which is wound around the drum and which extends forward from the drum, below and partially around the lower sheave, upward from the lower sheave to the upper sheave, over and partially around the upper sheave, and forward from the upper sheave to the bucket for moving the bucket generally horizontally relative to the main housing.
The invention also provides a dragline comprising a main housing including a generally horizontal platform, a boom extending forwardly from the main housing, a bucket suspended from the boom, a winding drum mounted on the platform for rotation about a generally horizontal axis, a fairlead mechanism mounted on the platform forward of the drum, the fairlead mechanism including an upper sheave mounted on a generally C-shaped upper bracket for rotation relative thereto about a generally horizontal upper axis, the upper bracket opening rearwardly and being mounted on the platform for pivotal movement about a generally vertical axis, and a lower sheave mounted on a generally C-shaped lower bracket for rotation relative thereto about a generally horizontal lower axis rearward and below the upper axis, the lower bracket being substantially identical to the upper bracket, opening forwardly and being mounted on the platform for pivotal movement about the generally vertical axis, such that the vertical axis extends between the upper and lower sheaves, and such that the upper and lower sheaves are supported for pivotal movement independently of each other about the vertical axis, the fairlead mechanism having no sheaves between the drum and the upper and lower sheaves, and a dragline rope which is wound around the drum and which extends forward from the drum, below the lower sheave, upward from the lower sheave to the upper sheave along the vertical axis, over the upper sheave, and forward from the upper sheave to the bucket for moving the bucket generally horizontally relative to the main housing, whereby the lower sheave pivots about the vertical axis in response to lateral movement of the rope along the drum and the upper sheave pivots about the vertical axis in response to lateral movement of the rope with the bucket.
The invention incorporates two identical sheaves with lower inertia requiring lower energy and shorter time intervals to match the speed of the rope to the speed of the sheaves during changes in rope direction. The invention also uses two identical swiveling brackets, the rearward one aligning the sheave with the drum as the rope unwinds and rewinds, thereby minimizing the fleet angle and allowing elimination of horizontal and vertical guide sheaves, and the forward one allowing the rope to follow the bucket while minimizing fleet angle effects. The low pivoting mass of the brackets enables the rope to move the assembly with less force and abrasion. The sheaves are also relocated to a higher position on the dragline, keeping the rope higher and further form the pit floor.
Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims and drawings.